Example embodiments of inventive concepts relate to a memory device, and more particularly, to a memory device, which determines, or efficiently determines, whether to perform a re-training operation to cause alignment between data and a clock signal after performing a training operation on the memory device, and a memory system including the memory device.
A memory controller may perform a training operation on a memory device after power-on to adjust an alignment condition, e.g. an improved and/or optimal alignment condition between data and a clock signal and then may control a memory operation such as a write operation and a read operation. When a specific (or, alternatively, predetermined) time passes after the training operation, a skew or a misalignment may occur between data and a clock signal due to a variation due to a memory operating environment or the like, and thus a write operation or a read operation may fail. Thus, a re-training operation may be performed on the memory device aligning the data with the clock signal. In order to perform the re-training operation, the memory controller may determine whether a memory operation fails, determine whether to perform the re-training operation based on the determination result, and control a re-training operation for the memory device.
However, when the memory controller performs operations, such as determining whether a memory operation fails and determining whether to perform the re-training operation, loss of time and memory performance deterioration due to the loss of time may occur.